[plt-scheme] Overriding the keymap in drscheme

From: Robby Findler (robby at cs.uchicago.edu)
Date: Tue Jul 25 14:32:08 EDT 2006

I wonder if another approach might make more sense for you (like
overriding on-insert/after-insert or maybe on-event). Perhaps you can
explain the bigger picture a little bit (like what the diva scheme
keymap binds and why chained keymaps are a problem)?

But if keymaps are what you really want, you might try subclassing
chain-to-keymap and other keymap methods to remember what happened and
then replay that when you remove the divascheme keymap.

You might also try calling to-dvascheme-mode at a different time (later
on), but that's still fragile.


At Tue, 25 Jul 2006 11:26:38 -0700 (PDT), Danny Yoo wrote:
> Hi everyone,
> Guillaume and I are running into a problem in DivaScheme when installs its 
> keymap. The thing is that I'm not just extending the existing keymap, but 
> overriding it entirely.  It is important that no other keybindings be 
> available when DivaScheme is on.
> Here's a snippet of the text mixin:
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>    (define (diva-link:text-mixin super%)
>      (class super%
>        ...
>        (define divascheme-keymap ...)
>        (define (to-divascheme-mode)
>          (preferences:set 'divascheme:on? #t)
>          (send divascheme-keymap chain-to-keymap (get-keymap) false)
>          (set-keymap divascheme-keymap))
>        (define/public (to-normal-mode)
>          (preferences:set 'divascheme:on? #f)
>          (set-keymap (first (send divascheme-keymap get-chained-keymaps))))
>        (let ([keymap (get-keymap)])
>          (send keymap add-function "diva:to-divascheme-mode"
>                (lambda (any event) (to-divascheme-mode)))
>          (send keymap map-function "f4" "diva:to-divascheme-mode"))
>        (when (preferences:get 'divascheme:on?)
>          (to-divascheme-mode))))
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> The scenario is the following: if 'divascheme:on? is true, DrScheme 
> installs the DivaScheme keymap midway through the initialization.  Tools 
> that load after DivaScheme break in two ways:
>     1.  Their keyboard bindings are active during the DivaScheme session 
> because they chain their keymap to the DivaScheme keymap.
>     2.  When we go back to normal mode, the set-keymap call restores a 
> keymap that does not have the tools that loaded after DivaScheme.
> The SET-KEYMAP in TO-NORMAL-MODE tries to alleviate problem #2 a bit.  If 
> a tool loads after DrScheme and chains its keymap at the end of the list, 
> the GET-CHAINED-KEYMAPS will recover it.  It's better than saving the 
> original (partially initialized) keymap in a global variable, and 
> restoring it in TO-NORMAL-MODE, but it's still not right.
> We haven't been able to find API support to do this properly.  Is there a 
> way to do this?
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